HYDRA: A Hypertext Model for Structuring Informal Requirements Representations 1

The ultimate measurement for software quality is the degree to which user needs are satisfied by the system. User needs are an essential input for developing a requirements specification and, in the first place, are most often represented using natural language, pictures, or graphics (informal representations). The consideration of user needs as a driving force throughout the development process is only possible if requirements traceability is assured. Therefore, the specified requirements must be related with their sources, e.g. the user needs. Hypertext offers a technology for enabling this interrelation. We propose a formal hypertext model, called HYDRA, for structuring informal requirements information. HYDRA enriches the quasi standard hypertext model Dexter by introducing typed hy- pertext nodes and links. HYDRA is used to structure informal information during the requirements engineering process by creating formal hypertext objects which refer to the informal represen- tations (or part of it). These formal objects are used to relate informal information with other representations (e.g. entity relationship diagrams, first order logic constraints). Moreover, the formal structure enables situated and selective retrieval of informal information. The creation of the formal objects as well as their relation with other representations is supported by the PRO-ART environment.